1. Field of the Invention
The present invention relates to a slow pull dryer, and more particularly, to a slow pull dryer which can smoothly remove particles floating over the surface of its hot water tank.
2. Description of the Prior Art
The slow pull dryer is commonly used in the cleaning process for removing particles. For example, during the formation of the disk, the substrate of the disk has some particles sticking on it, and these particles have to be removed to ensure the quality of the product. Therefore, in the formation of the disk, the slow pull dryer is utilized with the deionized hot water to wash off particles from the substrate of the disk.
Please refer to FIG. 1 and FIG. 2. FIG. 1 is a schematic diagram of the prior art slow pull dryer 10. FIG. 2 is a unit combination of the slow pull dryer 10 shown in FIG. 1. The prior art slow pull dryer 10 comprises a hot water tank 12 and a wave eliminator 14. The hot water tank 12 comprises four vertical side-walls 16 and a bottom plate 18 with a water hole 20 for filling hot water into the hot water tank 12. The hot water filled into the hot water tank 12 can spill out of the water tank 12 from the top sides of four vertical side-walls 16. The lower side of the wave eliminator 14 has a rectangular recess 22 facing downward. Each of the four side-walls of the wave eliminator 14 has a semicircle-shaped opening 24 for water to flow upward into the upper portion of the water tank 12. The wave eliminator 14 is installed at the bottom of the hot water tank 12, and the water hole 20 is positioned under the recess 22.
The upper side of the wave eliminator 14 contains a slope, and the wave eliminator 14 further comprises a vent pipe 28 installed on the higher end 26 of the slope. The hot water from the water hole 20 flows into the recess 22 of the wave eliminator 14 and its flowing speed is slowed down in the recess 22. The four openings 24 of the wave eliminator 14 allow the hot water in the recess 22 to flow upward into the upper portion of the water tank 12. As the water flow moves toward the top side of the vertical side-walls 16, particles and dusts drifting on the surface of the hot water can be carried out of the water tank 12 through the top side of the vertical side-walls 16. Besides, the air in the recess 22 will accumulate under the higher end 26 of the slope, and the accumulated air will pass out of the water tank 12 through the vent pipe 28.
Please refer to FIG. 3. FIG. 3 is a schematic diagram of the water flow in the water tank 12. In FIG. 3., the arrows and the helixes illustrate the flowing direction and the water turbulence, respectively. When the slow pull dryer 10 is used in the process for cleaning disks of the hard disk, the hot water from the water hole 20 into the recess 22 flows through the four openings 24 into the water tank 12 and mostly directly overflow the four vertical side-walls 16 of the water tank 12, because each position of the four opening 24 is at each of the four side-walls of the wave eliminator 14, respectively, and is very close to each of the four vertical side-walls 16 of the water tank 12, respectively. Also, the hot water forms water turbulence in the water tank 12, as shown in FIG. 3. As a result, it is very difficult for the slow pull dryer 10 to remove the particles from the substrate, and the particles drifting on the surface of the hot water will accumulate in the water tank 12 instead of flowing out of the water tank 12 which affects the quality of the process for cleaning the disk.
Because the hot deionized water is used in the slow pull dryer 10 to wash the substrate, and the hot water always comprises a lot of bubbles, the slow pull dryer 10 is equipped with the vent pipe 28 to pass the air gathered from the accumulated bubbles in the higher end 26 of the wave eliminator 14 out of the water tank 12. However, the discontinuous exhaust from the vent pipe 28 will cause the vibration of the vent pipe 28 and the water wave inside the water tank 12, therefore the substrate will have watermarks on it and hence the yield of the disks will be reduced. Besides, the discontinuous exhaust from the vent pipe 28 will generate noise as well.